The 2006 Biophysical Society Discussions, entitled "Molecular Motors-Point Counterpoint", is devoted to a critical evaluation of the current state of our knowledge about these diverse and pathophysiologically-relevant enzymatic machines-a discussion that will help resolve outstanding questions regarding motor function and lead to the development of new ideas about future directions. It will be held in Asilomar, California, from October 19-22, 2006. Although this field has made rapid progress in recent years, major unresolved questions remain. Do all motors have common structural elements that are shared by distinct motor superfamilies? If so, what does this tell us about what it takes to construct a motor? How do different motors convert the energy of ATP hydrolysis into force and movement, and are similar mechanisms used by all of these? How do motors determine their direction of movement, and how are they regulated? What can structural and enzymatic studies in vitro tell us about how a motor functions in the cell, and vice versa. A diverse group of speakers and participants with a broad range of expertise from molecular structure to single molecule mechanics to molecular genetics and cell biology will interact in a forum designed to critically evaluate our state of knowledge and develop new ideas regarding the future direction of research efforts in this field. Addressing these unresolved issues has become a particularly pressing concern as we have come to appreciate the central role that molecular motors play in the pathophysiology of a wide range of diseases-from cancer to atherosclerosis to amyotrophic lateral sclerosis to Alzheimer's disease. [unreadable] [unreadable] [unreadable]